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Autonomic nervous system tone measured by baroreflex sensitivity is depressed in patients with end-stage liver
1Department of Cardiology and The Liver Center, University of California, San Francisco, USA.
Objectives:
Chronic liver disease is often associated with impairment of autonomic nervous system (ANS) reflexes. Baroreflex sensitivity (BRS) testing is an inexpensive, relatively noninvasive test that can be used to assess ANS tone. The aims of the present study were to determine the prevalence of ANS dysfunction in cirrhotics who are being considered for liver transplantation and to explore the potential use of BRS as a prognostic tool in identifying patients awaiting transplantation who are at increased risk for death.
Methods:
We studied nine cirrhotics who were awaiting liver transplantation and seven controls without liver disease. BRS (ms/mm Hg) was measured using the phenylephrine method.
Results:
BRS (mean +/- SEM) (ms/mm Hg) was significantly lower in cirrhotics compared with controls (4.2 +/- 0.9 vs 21.1 +/- 3.8 ms/mm Hg; p < 0.05). Furthermore, BRS was lower in cirrhotics with hepatic encephalopathy compared with those without (2.6 +/- 0.9 vs 6.1 +/- 1.0 ms/mm Hg; p < 0.05) and there was a trend toward lower BRS values in Child-Pugh class C patients as compared with class B (3.8 +/- 1.3 vs 5.3 +/- 1.2 ms/mm Hg; p = 0.3). At follow-up (9 months), one patient had died and one underwent liver transplantation. These two patients also had the most severely impaired vagal tone (BRS = 0 and 1.2 ms/mm Hg, respectively).
Conclusions:
Vagal tone, as assessed by BRS, is markedly depressed in cirrhotic patients awaiting liver transplantation.